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. Author manuscript; available in PMC: 2021 Jan 26.
Published in final edited form as: Semin Nephrol. 2019 Jul;39(4):316–327. doi: 10.1016/j.semnephrol.2019.04.002

Table 4.

Indicator Dyes

pH range pKa Backbone Fluorophore Ex, nm Em, nm
6.0–8.0 7.5 SNARF 488 580 (iso) 640 (pH)
7.0–8.0 7.3 HPTS (pyranine) 410 (iso) 460 (pH) 511
6.5–7.5 6.98 BCECF 440 (iso) 490 (pH) 535
6.0–7.2 6.5 Fluorescein and carboxyfluorescein 492 514
4.5–6.0 5.2 LysoSensor green DND-189 443 505
4.2–5.7 4.7 Oregon green dyes 496 524
3.5–6.0 4.2 LysoSensor Yellow/blue DND-160 329 440
4–9* 6.8 pHrodo Red106 566 590
*

pHrodo succinimidyl ester shows a complex pH titration profile. Decreasing pH (from pH 9 to pH 2) produces a continuous (but nonlinear) fluorescence increase. This pH response profile typically changes upon conjugation of the dye to proteins and other biomolecules.

Abbreviations: BCECF, 2′,7′-Bis-(2-Carboxyethyl)-5-(and-6)-Carboxyfluorescein; HPTS, 8-hydroxypyrene-1,3,6-trisulfonic acid; iso, isobestic pH; pH, wavelength most sensitive to pH changes; SNARF, seminaphtorhadafluor.